The Templars are the long-running rival organization of the Assassins in the Assassin's Creed series.
The conflict between the two groups is the central struggle of the franchise. Assassins generally defend free will and oppose attempts to impose peace through control, while Templars seek order and stability, often through powerful institutions and Pieces of Eden. The games present both sides as organizations whose beliefs extend across centuries.
The Templars are inspired by the historical Knights Templar, but the game's version is a fictional secret organization that survives long after the medieval order was dissolved. In the modern era, Templar interests are represented largely through Abstergo Industries, a multinational corporation.
Abstergo is therefore related to the Templars but is not the same answer in every historical context. The Assassins are also called the Hidden Ones in ancient Egyptian settings, while the Templars' earlier counterparts are associated with the Order of the Ancients. These names show how the fictional conflict changes across different eras.